word-forming element meaning "before," from Old French pre- and Medieval Latin pre-, both from Latin prae (adverb and preposition) "before in time or place," from PIE *peri- (source also of Oscan prai, Umbrian pre, Sanskrit pare "thereupon," Greek parai "at," Gaulish are- "at, before," Lithuanian prie "at," Old Church Slavonic pri "at," Gothic faura, Old English fore "before"), extended form of root *per- (1) "forward," hence "beyond, in front of, before."
The Latin word was active in forming verbs. Also see prae-. Sometimes in Middle English muddled with words in pro- or per-.
late 14c., "reality," from Old French existence, from Medieval Latin existentia/exsistentia, from existentem/exsistentem (nominative existens/exsistens) "existent," present participle of Latin existere/exsistere "stand forth, come out, emerge; appear, be visible, come to light; arise, be produced; turn into," and, as a secondary meaning, "exist, be;" from ex "forth" (see ex-) + sistere "cause to stand," from PIE *si-st-, reduplicated form of root *sta- "to stand, make or be firm."
<a href="https://www.etymonline.com/word/pre-existence">Etymology of pre-existence by etymonline</a>
Harper, D. (n.d.). Etymology of pre-existence. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/pre-existence